There have been reports of an issue in which the error “Subtask CheckPrereqs execution failed: Check Tenant Prerequisites” is received when running Hybrid Configuration Wizard. Microsoft recently released a fix to remediate impact.

Symptoms:

When you use the Hybrid Configuration wizard to create or manage a hybrid environment that contains Microsoft Exchange Server 2013, you receive the following error message:

Subtask CheckPrereqs execution failed: Check Tenant Prerequisites

Deserialization fails due to one SerializationException:

Microsoft.Exchange.Compliance.Serialization.Formatters.BlockedTypeException: The type to be (de)serialized is not allowed: Microsoft.Exchange.Data.Directory.DirectoryBackendType

Cause:

This problem occurs because of recent changes to Exchange Online that prevent the Exchange 2013 Hybrid Configuration wizard from running correctly.

Resolution:

Download and install the latest cumulative update for Exchange 2013.

Hybrid Exchange 2013 Server Configuration Validation

1. From the Exchange 2013 PowerShell run Test-FederationTrust –userIdentity ckent@domain.com The output should look like the one below.

2. From the Exchange 2013 PowerShell run Test-FederationTrust –userIdentity (Onpremiseuser@domain.com). The output should be similar to the above.

3. Now run Get-Organizationrelationship |FL to check the Organization relationship and the output should look like the screenshot below.

4. Connect to Office 365 using the following script:

5. From Office 365 PowerShell, verify the TargetSharingEpr field is populated.

6. Once both servers are updated verify to see if you are able to view the free/busy information between the on-premise users and cloud users.

7. If you are still not able to do so, then you should run the Hybrid configuration wizard following the steps below:

Action	Screenshot
1.       In the EAC on an Exchange 2013 server in your on-premises organization, navigate to the Hybrid node.2.       In the Hybrid node, click Modify to start the Hybrid Configuration wizard. 3.       A confirmation window will appear to ensure that a Hybrid configuration change is to take place. Click Yes to confirm and begin the wizard.
4.       If you haven’t sign into Office 365 portal then you will be prompted to do so.5.       Sign into the portal with global Admin-level credentials.
6.       Select which server role you want to configure for bi-directional secure mail transport between the on-premises and Exchange Online organizations and have the option to enable centralized transport for outbound Exchange Online mail transport.For this configuration, we selected to configure my client access and mailbox servers for secure mail transport (typical)7.       Click Next to continue.
8.        Click Browse to display a list of client access servers in your on-premises Exchange organization.Select one or more servers you want to configure a Receive connector for bi-directional secure mail transport between the on-premises Exchange and Exchange Online organizations. Click Add and then click OK.  9.       Review configured servers for mail transport, then click Next.
10.    This list displays the digital certificates issued by a third-party certificate authority (CA) installed on the Mailbox server(s) selected in the previous step.Confirm the certificate being used and click Next.
11.    Enter the externally accessible FQDN for the on-premises organization. The EOP service in Office 365 uses this FQDN to configure the service connectors for secure mail transport between your Exchange organizations.12.    Enter the FQDN and click Next.
13.    Configure an account for on-premises administrative access and click Next
14.    Configure an account for Office 365 administrative access and click Next
15.    Once completed, click Update to make the necessary changes to the hybrid configuration and complete the wizard.

8. Check to see if you are able to view Free/busy information.

This post was written by Belal Khallad